Printing press blanket anchor bar

ABSTRACT

An improved end anchor for a printing press blanket is prepared by forming a bar with a bore or slot and filling the bore or slot with solidified resin around the end of the blanket.

United States Patent Roy D. Fountain 24 FM Ave., Lexington, Mas. 02173 Aug. 8, 1969 Division of Ser. No. 672.785. Oct. 4, I967, abandoned.

Patented Aug. 3, 197] inventor Appl. No. Filed PRINTING PRESS BLANKET ANCHOR BAR u.s.c1 101/41s.1, 161/44, 161/48, 264/252 FleldolSeareh 101/4151;

l6ll44,48, 100, 149; 29/243,58; 24/205.11 F, 265 EE; 264/252; 156/331 References Cited UNITED STATES PATENTS 12/1932 McElroy..... 101/4151 6/1946 Sprigg 10l/415.l 9/1951 Black et a1. 10l/415.1 5/1960 Ritzerfeld et a1.. 101/4151 5/1964 Simrns 156/331 1/1967 Kirkpatrick 101/4151 X 7/1968 Wassmann et a1. 101/4151 X 6/1969 Kettenring et a1. 156/331 X Primary ExaminerRobert E. Pulfrey Assistant Examiner-C. Coughenour AnomeysC. E. Parker, Metro Kalimon and William L.

Baker ABSTRACT: An improved end anchor for a printing press blanket is prepared by forming a bar with a bore or slot and filling the bore or slotwith solidified resin around the end of the blanket.

PATENTED we 3B?! FIG. 3

FIG; 4

INVENTOR ROY l). FOUNTAIN PRINTING PRESS BLANKET ANCBOR BAR This is a division of application, Ser. No. 672,785 filed Oct. 4, 1967 now abandoned.

This invention relates to ofiset and impression blankets, and particularly to anchoring means which prevent any concentration of strain from occurring in the blanket body. r

On the smaller machines, offset blankets frequently are stretched around and held on the offset cylinder by providing a series of hooks in a slot in the cylinder, engaging the blanket over the hooks, and catching the free end of the blanket over a second group of hooks which can be rotated by a ratchet- Iocked reel to pull the blanket completely into tight contact with the cylinder.

Somewhat larger presses equip the blanket with an anchor bar which frequently fits into a specially contoured slot. The opposite end of the blanket is also equipped with an anchor bar, and this may be engaged by a ratchet-locked reel which pulls the blanket tightly into place on the cylinder.

When anchor bars are used, it is usual to form them from steel bars or steel strips riveted together with the blanket pinched between them. Consequently, numbers of rivets pass through the bars and through the body of the blanket. The rivets cut some threads, and make uneven strain inevitable.

In order to prevent any creep, it is necessary for the blanket to be pulled around the cylinder under considerable tension. But the method of holding the blanket between bars that are riveted together concentrates the strain on the blanket material in a series of longitudinal stress lines extending between the rivet on one end and the rivet on the other end of the blanket. The effect of this concentrated strain is to produce a waviness, and actually changes the thickness of the blanket in an area which is adjacent to the anchored portion on either end.

If the length of the printed page is materially less than the length of the blanket, the deleterious effect of such a concentration of stress is not serious, but if the attempt is made to print a page which is substantially of the same length as :the blanket, changes in the color layofi' will be noted immediately adjacent the blanket anchorages for, as is well known, very slight differences in elevation amounting to only fractional thousandths of an inch produce very large changes in the color or intensity of the image on the paper.

We have discovered that it is possible to attach anchor bars to blankets whether they be designed as offset blankets or as impression blankets in such a way that there is no concentration of stress as the blanket is tensioned around the cylinder. Consequently, the surface of the blanket lies uniformly in a plane and remains free from any differences in elevation.

An additional advantage of the invention lies in the fact that attachment of the blanket to the anchor bars can be made simply, accurately, and very inexpensively, and that no danger of cutting or pinching the blanket can develop as the arichor bars are attached.

The invention will be understood from the drawing in which:

FIG. 1 is a perspective view of a preferred form of anchbr bar,

FIG. 2 is a perspective view of one end of a blanket equipped with the improved anchor bar,

FIG. 3 is a cross section of an anchor bar formed from sheet metal, and

FIG. 4 is a cross section of an alternative form of an extruded anchor bar.

In generalized form, the improved anchor bar may be described as a bar, 10, having a bore portion, 11, from which rise two arms, 12, and 13, which, fitted across the ends of a blanket, l4, embrace the front and rear surfaces of the blanket.

The preferred form of anchor bar (FIG. 1) is a metallic extrusion, 10, having a longitudinal bore, 15, and an intersecting slot, 16, formed inwardly from the upper face, 17, of bar, 10, and terminating in the bore, 15. The bore is wider than the slot. It appears tube of some advantage to commence the slot,

16, as close as possible to one edge of the bar, but angle the cut so that the slot, 16, intersects the bore, 15, approximately along the centerline.

When the blanket, 14, is fixed in the holding means of the press cylinder, it is bent downwardly over the wider shoulder, 18, of the arm, 12. This appears to offer a slight advantage over a slot cut parallel to the faces of the bar as is shown at 16a on the bar, 100, FIG. 4. Alternatively, it is possible to form the bars of sheet metal, and in this case a configuration shown at 106 in FIG. 3 is very effective. No bore in the sense of the bore, 1!, exists in the sheet 'metal form. Instead, the entire space included within thearms, 19 and 21, performs the function of the bore, 15. In the smaller presses, aluminum extrusions are satisfactory. For the larger, heavier presses, the strength and ruggedness of steel is preferable.

The anchor bars are attached to the blankets by either of the following procedures:

I. The ends of the blanket, 14, are accurately squared by a cut made exactly to the longitudinal margins. A length of the extrusion, l0, equaling the width of the blanket, 14, is prepared, and a' rod of a thermoplastic adhesive having a diameter which loosely fits the bore, 15, is pushed into the bore. Assuming that therod of adhesive is the copolyester of terephthalic and'isophthalic acids having a crystal melt temperature between 338 and 350 F., the bar, 10, is then raised to a temperature of between 400 and 420 F whereupon the rod becomes fluid. The squared end of the blanket is then pushed down through the slot, 16, until it contacts with the lower wall of the bore, 15. Meanwhile, the fluid resin flows around and about the end of the blanket, and some pushes up on both sides of the blanket lying within the slot, 16.

As soon as the blanket has been seated in the molten resin, it is held in any suitable vice or jig which will prevent any relative movement between the bar, 10, and the blanket, 14, while the resinous mass, 22, cools.

There are a considerablenumber of thermoplastic compositions which give satisfactory performance, e.g. nylons and the polyamide resins formed by the reaction of diethylene, triamine, and ethylene diamine reacted with dimeriz ed linoleic acid and polyamides formed by the reaction of ethylene diamine alone with dimerized linoleic acids. In the above two instances, the ball and ring softening points of the hot melt resins were 270 300 F., and 226 F., respectively. The temperature to which the bar tnustbe heated to cause the thermoplastic to melt is, of course, a function of the thermoplastic itself. It is, however, advantageous to heat the bar a number of degrees above the actual melt temperature so that the molten adhesive will flow easily, and bed the blanket properly.

2. Instead of using hot melt resins, the blanket can be secured to the anchoring bars by a curing-type adhesive and, more specifically, an epoxy or polyester resin. A very considerable number of commercial adhesives based on these resins are available and anchor the blanket securely to the anchor bars, 10. As contrasted with hot melt resins which cool promptly, the curing-type -adhesives require a considerable time for the curing reaction to take place. Usually a curing period extending overnight at atmospheric temperatures is sufficient, but is is quite necessary that during this time there should be no relative movement of the blanket and bar. As a result, during the whole curing period it is necessary to hold both the bar and the blanket in a suitable jig.

It is obvious that the external configuration of the bars will be such as may be demanded by the design of the tensioning reels or takeup devices in the press cylinders. The designs shown are examples of fonns suitable for use in a number of presses. The characteristic feature of the invention, however, is a bar bearing a slot into which the blanket may be fitted, having an enlarged area at the bottom of the slot to hold the adhesive.

Small blankets foroflice bfi'set type presses are satisfactorily anchored in extrusions such as shown in FIG. 3, while blankets forthe larger oflset presses or impression blankets are satisfactorily anchored, e.g. in extrusions having the cross sections as shown-in FIGS. 1 and 4.

Example 1 completely in the molten nylon 66. The bar and nylon were allowed to cool. When subjected to a pull exerted between anchor bars, this blanket withstood a pull of 120 lbs. per linear inch. When pulled up taut around the press cylinder, the stress on the blanket was uniform and no indication of concentrated stress, as around rivets, existed.

Example 2 An offset blanket having a nominal thickness of 0.075 inches was anchored in an aluminum bar having a %X% inch cross section channeled with a 5/64 inch slot 3/16 inch deep terminating in a circular bore 3/ l6 inch in diameter. The squared end of the blanket was pushed into the slot and bore, which previously had been filled with an activated commercial epoxy resin supplied by the Devcon Corp. The blanket was clamped for 24 hours in a holding vice which prevented relative movement between the bar and the blanket. At the end of the time, the resin had hardened. The blanket was then subjected to a tension test, one of the bars being restrained and the other end being jacked backwards in increments. At a pull equaling 160 lbs. per linear inch of blanket, the test was stopped. There was no rupture, pulling away, or wrinkling during the time that the tension was applied. The blanket was then placed on the cylinder of a press and tensioned. No wrinkling or strains were evident. Substantially the same results were secured with epoxy resin adhesives obtained from other commercial sources.

In all designs the stress was uniformly distributed across the width of the blanket. There are no concentrated stresses as about rivet holes to cause unevenness, strain, and waviness, and all danger of pinching or cutting as the rivet holes ar punched in the blanket is eliminated.

I claim:

1. A printing press blanket provided with an end-anchoring bar wherein the anchor bar is a substantially rectangular bar having a longitudinal bore, a slot cut in one face and extending into said bore, the bore being wider than the slot, the said slot extending along a line adjacent one corner of said bar angularly to intersect said bore substantially on the central plane of said bar, the said blanket being fitted in the slot and in the fore and secured in the bar by a solidified resin, the resin filling the free space in the slot and the bore and being adherent to both the blanket substance and to the inner surfaces of the bar.

2. A printing press blanket as claimed in claim 1, wherein the solidified resin is a thermoplastic substance having a melt temperature of between approximately 270 and 350 F.

3. A printing press blanket as claimed in claim 1, wherein the solidified resin is an epoxy resin compound.

4. A printing press blanket as claimed in claim 1 wherein the solidified resin is nylon. 

1. A printing press blanket provided with an end-anchoring bar wherein the anchor bar is a substantially rectangular bar having a longitudinal bore, a slot cut in one face and extending into said bore, the bore being wider thaN the slot, the said slot extending along a line adjacent one corner of said bar angularly to intersect said bore substantially on the central plane of said bar, the said blanket being fitted in the slot and in the fore and secured in the bar by a solidified resin, the resin filling the free space in the slot and the bore and being adherent to both the blanket substance and to the inner surfaces of the bar.
 2. A printing press blanket as claimed in claim 1, wherein the solidified resin is a thermoplastic substance having a melt temperature of between approximately 270* and 350* F.
 3. A printing press blanket as claimed in claim 1, wherein the solidified resin is an epoxy resin compound.
 4. A printing press blanket as claimed in claim 1 wherein the solidified resin is nylon. 